The present invention relates to a new and improved construction of an apparatus for adjusting in a projectile, after firing the projectile from a firing weapon through the muzzle of said firing weapon, a counter controlling a time or delayed action fuze in the projectile.
In its more particular aspects, the present invention specifically relates to a new and improved apparatus for adjusting in a projectile, after firing the projectile from a firing weapon through the muzzle of such firing weapon, a counter which controls a time or delayed action fuze in the projectile. The counter is inductively set by means of a transmitter or induction coil which is mounted at the firing weapon downstream from a muzzle velocity measuring device or means, and a receiver coil which is located in the time or delayed action fuze of the projectile. The counter for starting the time or delayed action fuze may be typically set as a function of the muzzle velocity which is measured by the muzzle velocity measuring device or means.
In an apparatus of this type as known, for example, from U.S. Pat. No. 4,022,102, granted May 10, 1977, the transmitter or induction coil is capable of transmitting approximately 8 to 10 pulses during the passage of the projectile through such transmitter coil. In order to distinctly transmit, from the transmitter or induction coil to the receiver coil, two different digital signals, namely the digital signals "0" and "1", by means of this prior art device, the transmitter coil is magnetized in one direction for transmitting the digital signal "0" and in the opposite direction for transmitting the digital signal "1". For this purpose, a positive voltage is applied to the transmitter or induction coil for one of the two digital signals and, thereafter, a negative voltage is applied to the transmitter or induction coil for transmitting the other one of the two digital signals. Consequently, the current is selectively flowing or passed through the transmitter or induction coil in one or in the other, i.e. the opposite direction. The transmitter or induction coil is thereby fully magnetized for the digital signal "0" as well as for the digital signal "1". The transmitter or induction coil is not magnetized during the intervals between the two digital signals "0" and "1".
When utilizing this type of signal transmission, there is required between the individual digital signals a dead time or dead time interval which amounts to approximately the tenfold of the pulse duration of each one of the digital signals. When the transmitter or induction coil has a length of 12 cm and the muzzle velocity of the fired projectile is assumed to be 1200 m/sec, only a limited time period is available for the transmitter or induction coil for transmitting at least 8 to 10 pulses during passage of the projectile through the transmitter or induction coil and, therefore, a transmission frequency of 100 kHz is required.
In a further arrangement of this type as known, for example, from German Patent Publication No. 2,316,976, published Oct. 17, 1974, a control coil is mounted at the muzzle of the weapon barrel. During the throughpassing flight of the projectile, the time period for starting or activating the fuze is determined by means of a receiver in the projectile fuze.
In this known arrangement, a current passes through the control coil and the magnitude of this current is a measure of the value intended to be adjusted or set. The receiver circuit contains a receiver coil and means for evaluating the magnitude of the voltage which is induced in the receiver coil during the throughpassing flight of the projectile through the control coil.
Such arrangement is not sufficiently precise for present requirements. The magnitude of the voltage which is induced in the receiver coil during the throughpassing flight of the projectile through the control coil, firstly, is dependent upon whether the projectile exactly centrally flies or passes through the control coil and, secondly, whether the projectile flies or passes through the control coil exactly at the desired muzzle velocity.